Implantable prostheses are commonly used to replace or augment body tissue. In the case of breast cancer, it is sometimes necessary to remove some or all of the mammary gland and surrounding tissue which creates a void that can be filled with a fluid-filled implantable prosthesis. The implant serves to support surrounding tissue and to maintain the appearance of the body. The restoration of the normal appearance of the body has an extremely beneficial psychological effect on post-operative patients, alleviating much of the shock and depression that often follows extensive surgical procedures.
Soft implantable prostheses typically include a relatively thin and quite flexible envelope or shell made of silicone elastomer. The shell is filled either with a silicone gel or with a physiologic saline solution. The filling of the shell may take place before or after the shell is implanted in the patient.
A saline-filled implant includes an outer shell of several layers of silicone elastomer having a valve or fill port on one side. The prosthesis is typically implanted into the breast cavity in an empty or only partially filled state. The implant is then inflated to its final size by means of the valve or fill port. This helps reduce the size of the needed incision, and enables a surgeon to adjust and even microadjust the volume of the implant. Unfortunately, the valve or fill port is sometimes noticeable to the touch.
Prior to implantation of a more permanent prosthesis, it is common practice to utilize a more temporary implant, for example, what is known as a “tissue expander” in order to gradually create the space necessary for the more permanent prosthesis. Essentially, a tissue expander comprises an inflatable body, having an inflation valve connected thereto. The valve may be formed into the inflatable body itself or may be remotely located and connected to the inflatable body by means of an elongated conduit.
The inflatable body of the tissue expander is placed subcutaneously in the patient, at the location of where tissue is to be expanded. The inflation valve, whether on the implant or remote thereto, is also subcutaneously positioned or implanted, and is configured to allow gradual introduction of fluid, typically saline, into the inflation body, by injection with a syringe. After gradual inflation at pre-determined intervals, the skin and subcutaneous tissues overlying the expander are consequently caused to expand in response to the pressure exerted upon such tissues by the inflatable body as solution is gradually introduced therein.
After gradual inflation at pre-determined intervals, which may extend over weeks or months, the skin and subcutaneous tissue will expand to the point where further medical procedures can be performed, such as the permanent implantation of a prosthesis, plastic and reconstructive surgery, or for use of the skin and subcutaneous tissue for use in some other part of the body.
During a mastectomy, a surgeon often removes skin as well as breast tissue, leaving the chest tissues flat and tight. To create a breast-shaped space for a reconstructive implant, a tissue expander is sometimes used as described above.
In any event, it should be appreciated that locating the fill valve on the prosthesis or tissue expander requires considerable practitioner skill. Attempts to make products which facilitate this include the development of various products having structure, for example, embedded magnets or a raised ring, for assisting physicians in locating the valve.
Bark, et al., U.S. Pat. No. 5,074,878, discloses a tissue expander. According to Bark et al., the tissue expander comprises a closed shell structure having a wall formed of a needle-penetrable material which has self-sealing characteristics. The shell includes a flowable self-sealing layer sandwiched between layers of non-flowable elastomeric material.
There still remains a need for better inflatable implant shells.